1. Field of the Invention
The current invention is related to a high energy efficiency propeller which is developed to use in aircrafts and sea vehicles, pumping systems, wind turbines and hydro-energy turbines.
Said invention is related to propeller blades which are distributed around propeller hub and positioned so as to set an angle with the axis of propeller hub (x), to a concave curvilinear contact surface which are formed on the front surface of said blades that push water and to a convex outlet radius which follows this contact surface and is shorter than said contact surface.
2. Description of Related Art including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
As it is known, the ship propeller is a driving component which is used to move the vessels and makes a rotational motion by the drive. The propellers produced in various forms transform the power generated by the hull machines to propellant power to move the vessel on the water. The propeller accelerates water flowing through it and the reaction resulted from increase of motion quantity caused by this accelerated flow pushes the vessel forward. The increase of motion quantity is ensured either by a slight speed increase in a huge water mass (large, slow operating propellers) or by a big speed increase in a small water mass (small, high speed propellers). The first system has higher efficiency.
The shape of the hull of ship has a significant effect on water flow towards propeller. As the ship drags a part of water mass with while moving ahead, the relative headway of the propeller inside water is lower than the real speed of the ship.
The axial speed of water differs in various parts of the propeller. Hence, each rotating blade passes through water areas having high and low speeds. In general the relative water speed reaches its lowest level while the blade is in its highest position (vertical) and it reaches its highest level while the blade is in the lowest position. As a result, the force applied by the blades varies continuously in a certain range of values, and subsequently, vibration, endurance and cavitation problems are encountered.
Cavitation: the propeller blades in aerofoil shape function as wing flaps. Water passing through circumference of the blade creates a low pressure in front while it increases pressure at the back. A big part of propeller effect occurs in the low pressure area. If the pressure drops below the evaporation pressure of water at any point, bubbles occur in the water. The propellers which are used in the sea due to cavitation are made with much larger blades than those used in the air.
One of the important problems of making propellers is that the ship force is transformed to the repelling force in the preliminary specified rotation number. This is dependent on propeller pitch on a large scale. The facts of that the pitch is dependent on the angle made with the flow direction of the blades and that the generated repelling force and pressure are resulted from the motion of the propeller make the pitch important as regards cavitation. Thus, any cavitation which may occur is decreased by arranging the pitch so as to be changed on the whole surface of the blade for each value of the radius.
As for the propellers; in a preferred patent application, U.S. Pat. No. 4,1318,671, American origin, dated 1982; in this patent, a special structure is referred to; this structure is related to use polymer surface on triquetrous blade edges in order to decrease energy losses arising on ship propellers and related to decrease surface losses causing to turbulence. In the current invention, a surface pass in three different angles on the propeller blade is used to increase energy efficiency.
In the U.S. Pat. No. 4,171,183, dated 16 Oct. 1979; a mechanism which may change the propeller blade angles purposing to increase energy efficiency is proposed differently. The blade angle varying depending on the speed (pitch control) can be used as an attachment in the propeller design proposed herein. The blade angle control is independent from the main concept of the design mentioned here. In the U.S. Pat. No. 4,932,908 and dated 12 Jun. 1990, the propeller blade countervails the fluid flowing in with an oblique shaft angle, purposing to minimize the viscous friction on the propeller blade, to minimize kinetic energy losses on the blade and to increase total energy efficiency. In the current invention, the triquetrous propeller blade profile and total energy conversion efficiency are increased without causing to a difference as to the shaft.
The U.S. Pat. No. 6,877,692B2, dated 12 Apr. 2005 refers to reverse phase oscillation of two propeller blades to each other purposing to increase energy conversion efficiency in the fluid, and to ensure the compressed fluid generates repelling force.
The U.S. Pat. No. 4,073,601, dated 14 Feb. 1978 contains generating propeller blade surfaces in high speeds. While the current invention has a similar mechanism decreasing cavitation effect, the main difference is that the reverse direction input (attack) angle and release (trailing) angles have specific values increasing energy conversion efficiency simultaneously, and that the blade profile is designed accordingly.